1. Field of the Invention:
The present invention relates to a developing method for an electrostatic latent image, and particularly to a developing method obtained a multicolor images.
2. Description of the Prior Art:
The typical method for making an electrostatic latent image into the multicolored image is relating to an electrophotographic method for a color image.
Inter alia, there is such a method that document is exposed, the reflected light is color separation through an optical filter and the color-separated lights are used as the exposure light source to a photoreceptor, and that a series of charging and exposing, developing, and transfer processes is successively repeated four times in combination with the developments each to be made with yellow, magenta, cyan and black toners, respectively. Besides the above, there is another method in which heteropolar electrostatic latent images are produced on the same photoreceptor and then the developments are made with black toner and red toner.
As much these multicolor-images are of the more desired because a colored image information can still further be added, as compared with a black and white image information, it is needed to use for an apparatus provided developing devices respectively corresponding to each color for obtaining colored image information.
Accordingly, above apparatus have caused the following defects
(1) that the apparatus becomes larger in size and more expensive in cost,
(2) that a color shearing accuracy in repeating operations should be indispensable, and
(3) that every copy-time drags on.
From the viewpoints of above defects, there have tried to make a developing device compact in size by mixing up two kinds of colored developers of which colors are different from each other in the same developing device (for example, refer to Japanese Patent Publication No. 30625/1980). However, there will cause the defects as mentioned below if such a simple mixture of two different color developers alone is used as quoted in the abovementioned citation:
(1) Even an area where is not formed an electrostatic latent image is developed, that is, a fog is formed therein.
(2) Color reproduction is worsen for causing from the other unnecessary developer intermixed into the proper developer forming a developed image, that is, a color turbidity is occured.
(3) A sharp and clear image cannot be obtained.